Question

先化简,再求值x/x的平方-2xy+y平方×(x-y)+(2x+2/x-y-2)，其中x，y满足方程组x+2y=3，x-y=-5.

Answer 1

x/x的平方-2xy+y平方×(x-y)+(2x+2/x-y-2)
=x/(x-y)²×(x-y)+(2x+2/x-y-2)
=x/(x-y)+(2x+2)/(x-y)-2
=(3x+2)/(x-y)-2
=(x+2y+2)/(x-y)
=(3+2)/(-5)
=-1

Answer 2

原式=x/(x-y)²×(x-y)+(2x+2-2x+2y)/(x-y)
=x/(x-y)+(2+2y)/(x-y)
=(x+2y+2)/(x-y)
=(3+2)/(-5)
=-1